Realization of anisotropic compass model on the diamond lattice of Cu2+^{2+} in CuAl2_2O4_4

Spin-orbit (SO) Mott insulators are regarded as a new paradigm of magnetic materials, whose properties are largely influenced by SO coupling and featured by highly anisotropic bond-dependent exchange interactions between the spin-orbital entangled Kramers doublets, as typically manifested in $5d$ iridates. Here, we propose that a very similar situation can be realized in cuprates when the Cu$^{2+}$ ions reside in a tetrahedral environment, like in spinel compounds. Using first-principles electronic structure calculations, we construct a realistic model for the diamond lattice of the Cu$^{2+}$ ions in CuAl$_2$O$_4$ and show that the magnetic properties of this compound are largely controlled by anisotropic compass-type exchange interactions that dramatically modify the magnetic ground state by lifting the spiral spin-liquid degeneracy and stabilizing a commensurate single-$\boldsymbol{q}$ spiral

Effects of Crystal Structure and the On-Site Coulomb Interactions on the Electronic and Magnetic Structure of Pyrochlores A2A_2Mo2_2O7_7 (A= Y, Gd, and Nd)

Being motivated by recent experimental studies, we investigate magnetic structures of the Mo pyrochlores $A_2$Mo$_2$O$_7$ ($A$= Y, Nd, and Gd) and their impact on the electronic properties. The latter are closely related with the behavior of twelve Mo($t_{2g}$) bands, located near the Fermi level and well separated from the rest of the spectrum. We use a mean-field Hartree-Fock approach, which combines fine details of the electronic structure for these bands, extracted from the conventional calculations in the local-density approximation, the spin-orbit interaction, and the on-site Coulomb interactions amongst the Mo(4d) electrons, treated in the most general rotationally invariant form. The Coulomb repulsion U plays a very important role in the problem, and the semi-empirical value U$\sim$1.5-2.5 eV accounts simultaneously for the metal-insulator (M-I) transition, the ferromagnetic (FM) - spin-glass (SG) transition, and for the observed enhancement of the anomalous Hall effect (AHE). The M-I transition is mainly controlled by $U$. The magnetic structure at the metallic side is nearly collinear FM, due to the double exchange mechanism. The transition into the insulating state is accompanied by the large canting of spin and orbital magnetic moments. The sign of exchange interactions in the insulating state is controlled by the Mo-Mo distances. Smaller distances favor the antiferromagnetic coupling, which preludes the SG behavior in the frustrated pyrochlore lattice. Large AHE is expected in the nearly collinear FM state, near the point of M-I transition, and is related with the unquenched orbital magnetization at the Mo sites. We also predict large magneto-optical effect in the same FM compounds.Comment: 26 pages, 17 figures (low resolution is used for Figs. 6, 8, and 9, please contact directly if you need the originals), 1 tabl

Improvement of a test-system for the botulinus toxin screening in dot-immunoanalysis

We constructed a test system for dot-immunoassay (DIA) to accelerate definition and identification of botulinus toxins and also to refuse from application of laboratory animals for routine screening of clinical samples, foodstuff and environments. This system permitted to detect botulinus toxin during approximately 2 h in the tested samples. Sensitivity of this DIA in some cases exceeded the mice biotest. This improved method has minimum reaction to nonspecific exposures from the investigated biological substrata. It is simple to conduct. It is high efficient and expressive, does not require to use expensive equipment and the reactants, special training for the personnel. Lyophilization conditions for the immune reagents used for the test system preparation for botulinus toxin dot-immunoassay were selected. High sensitivity, specificity of the analysis are remained, stability of the preparations (periods of storage) is increased. This method is convenient to use in field conditions at extreme situations, in particular, in mobile autolaboratories for epidemiological survey

RUSSIAN ENGINEERING TEACHERS AS AN IMPORTANT PART OF IGIP

The paper highlights the milestones of the history of the International Society for Engineering Pedagogy (IGIP) from 1972 until now. Professor A. Melezinek was a founder of the society; he developed its structure that survived to the present time. Now his pedagogical ideas are being developed and revised to reflect the changes in the goals and contents of engineering education, new methods, means of training and control, modern communication capabilities. Global challenges, problems of sustainable development and construction of the so-called “Resilient Society” were the main topics of the last Annual IGIP conferences. Globalization has led to the organization of the International Federation of Engineering Education Societies (IFEES). IGIP was one of its founders in 2006. We discuss different aspects of cooperation between Russian technical universities and IGIP, which began in 1995. Regional IGIP conferences and round tables are one of the aspects of such cooperation. The importance of this interaction for the Russian scientific school of engineering education is emphasized

Optical Investigations of Charge Gap in Orbital Ordered La1/2Sr3/2MnO4

Temperature and polarization dependent electronic structure of La1/2Sr3/2MnO4 were investigated by optical conductivity analyses. With decreasing temperature, for E//ab, a broad mid-infrared (MIR) peak of La1/2Sr3/2MnO4 becomes narrower and moves to the higher frequency, while that of Nd1/2Sr3/2MnO4 nearly temperature independent. We showed that the MIR peak in La1/2Sr3/2MnO4 originates from orbital ordering associated with CE-type magnetic ordering and that the Jahn-Teller distortion has a significant influence on the width and the position of the MIR peak.Comment: 10 pages, 4 figure

Manganites at Quarter Filling: Role of Jahn-Teller Interactions

We have analyzed different correlation functions in a realistic spin-orbital model for half-doped manganites. Using a finite-temperature diagonalization technique the CE phase was found in the charge-ordered phase in the case of small antiferromagnetic interactions between $t_{2g}$ electrons. It is shown that a key ingredient responsible for stabilization of the CE-type spin and orbital-ordered state is the cooperative Jahn-Teller (JT) interaction between next-nearest Mn$^{+3}$ neighbors mediated by the breathing mode distortion of Mn$^{+4}$ octahedra and displacements of Mn$^{+4}$ ions. The topological phase factor in the Mn-Mn hopping leading to gap formation in one-dimensional models for the CE phase as well as the nearest neighbor JT coupling are not able to produce the zigzag chains typical for the CE phase in our model.Comment: 16 pages with 16 figures, contains a more detailed parameter estimate based on the structural data by Radaelli et al. (accepted for publication in Phys. Rev. B

Oscillatory Exchange Coupling and Positive Magnetoresistance in Epitaxial Oxide Heterostructures

Oscillations in the exchange coupling between ferromagnetic $La_{2/3}Ba_{1/3}MnO_3$ layers with paramagnetic $LaNiO_3$ spacer layer thickness has been observed in epitaxial heterostructures of the two oxides. This behavior is explained within the RKKY model employing an {\it ab initio} calculated band structure of $LaNiO_3$, taking into account strong electron scattering in the spacer. Antiferromagnetically coupled superlattices exhibit a positive current-in-plane magnetoresistance.Comment: 4 pages (RevTeX), 5 figures (EPS

THE KINETICS OF DECOMPOSITION OF SUPERCOOLED AUSTENITE OF STEEL 26CrNi3Mo2V UNDER CONTINUOUS COOLING

В работе изучена кинетика фазовых превращений стали 26ХН3М2ФА при непрерывном охлаждении. Построена термокинетическая диаграмма распада переохлажденного аустенита стали 26ХН3М2ФА.Установлено, что исследуемый материал обладает высокой устойчивостью к распаду по диффузионному механизму.The kinetics of phase transformations is considered. It is established that the steel 26CrNi3Mo2V has a high resistance to decay by the perlite mechanism. TTS diagram is constructed.Работа выполнена при финансовой поддержке Министерства образования и науки Российской Федерации рамках реализации федеральной целевой программы «Исследования и разработки по приоритетным направлениям развития научно-технологического комплекса России на 2014 - 2020 годы» (шифр заявки «2015-14-579-0173-366»). Соглашение о предоставлении субсидии №14.578.21.0114 от 27 октября 2015г. Уникальный идентификатор ПНИЭР - RFMEFI57815X0114

Structural, magnetic and electrical properties of single crystalline La_(1-x)Sr_xMnO_3 for 0.4 < x < 0.85

We report on structural, magnetic and electrical properties of Sr-doped LaMnO_3 single crystals for doping levels 0.4 < x < 0.85. The complex structural and magnetic phase diagram can only be explained assuming significant contributions from the orbital degrees of freedom. Close to x = 0.6 a ferromagnetic metal is followed by an antiferromagnetic metallic phase below 200 K. This antiferromagnetic metallic phase exists in a monoclinic crystallographic structure. Following theoretical predictions this metallic antiferromagnet is expected to reveal an (x^2-y^2)-type orbital order. For higher Sr concentrations an antiferromagnetic insulator is established below room temperature.Comment: 8 pages, 7 figure

Терапия с последовательным применением ритуксимаба и белимумаба у пациентов с системной красной волчанкой

Objective: to determine the efficiency of sequential (combined) therapy with rituximab (RTM) and belimumab (BLM) in patients with active systemic lupus erythematosus (SLE).Patients and methods. Twelve patients with true SLE having moderate-to-high activity were followed up. Six of them were noted to have skin and articular manifestations and 6 had kidney damage, vasculitis. The patients took RTM at 500–2000-mg doses, with 6-methylprednisolone as premedication, whereupon they were prescribed BLM according to the standard regimen of 10 mg/kg once monthly. The follow-up period was 1 year. At baseline and every three months after RTM administration, the efficiency and tolerability of therapy were evaluated, the concentrations of autoantibodies and complement components was estimated, and the dose of oral glucocorticoids (GCs) was recorded.Results and discussion. During combined therapy with the biological agents (BAs), there was a considerable clinical and laboratory improvement: reductions in disease activity (median (Me) SLEDAI-2K scores were 12 [9.5; 17] at baseline and 2 [2; 6] at Visit 4), the Me concentrations of anti-double-stranded DNA (anti-ds-DNA) antibodies, 101 [39; 250] and 28 [6; 112] U/ml, respectively; those of complement component 3 (C3), 0.44 [0.39; 0.59] and 0.83 [0.81; 0.87] g/L, respectively; and those of complement C4, 0.06 [0.031; 0.1] and 0.16 [0.15; 0.18] g/l, respectively). Most patients received the medium and low doses of oral GCs as initiating therapy. During the year, the dose of GCs was reduced by more than a quarter and they could be completely discontinued.evaluated, the concentrations of autoantibodies and complement components was estimated, and the dose of oral glucocorticoids (GCs) was recorded. Results and discussion. During combined therapy with the biological agents (BAs), there was a considerable clinical and laboratory improvement: reductions in disease activity (median (Me) SLEDAI-2K scores were 12 [9.5; 17] at baseline and 2 [2; 6] at Visit 4), the Me concentrations of anti-double-stranded DNA (anti-ds-DNA) antibodies, 101 [39; 250] and 28 [6; 112] U/ml, respectively; those of complement component 3 (C3), 0.44 [0.39; 0.59] and 0.83 [0.81; 0.87] g/L, respectively; and those of complement C4, 0.06 [0.031; 0.1] and 0.16 [0.15; 0.18] g/l, respectively). Most patients received the medium and low doses of oral GCs as initiating therapy. During the year, the dose of GCs was reduced by more than a quarter and they could be completely discontinued. Conclusion. Combined biological therapy with RTM and BLM is a promising treatment for active SLE. The use of this regimen promotes a rapid and effective reduction in disease activity, normalization of laboratory markers of SLE (anti-ds-DNA antibody and complement C3 and C4 levels), and decreases in the dose of oral GCs and, as a consequence, in the risk of irreversible organ damages.. Combined biological therapy with RTM and BLM is a promising treatment for active SLE. The use of this regimen promotes a rapid and effective reduction in disease activity, normalization of laboratory markers of SLE (anti-ds-DNA antibody and complement C3 and C4 levels), and decreases in the dose of oral GCs and, as a consequence, in the risk of irreversible organ damages.Цель исследования – определение эффективности последовательной (комбинированной) терапии с применением ритукисмаба (РТМ) и белимумаба (БЛМ) у пациентов с активной системной красной волчанкой (СКВ).Пациенты и методы. Под наблюдением находилось 12 пациентов с достоверной СКВ высокой и средней степени активности. У 6 из них отмечались кожно-суставные проявления, у 6 – поражение почек, васкулит. Пациенты получали РТМ в дозе 500–2000 мг с премедикацией 6-метилпреднизолоном, после чего им назначали БЛМ по стандартной схеме 10 мг/кг 1 раз в месяц. Срок наблюдения – 1 год. Исходно после введения РТМ и затем каждые 3 мес оценивали эффективность и переносимость терапии, определяли концентрацию аутоантител и компонентов комплемента, регистрировали дозу пероральных глюкокортикоидов (ГК).Результаты и обсуждение. На фоне комбинированной терапии генно-инженерными биологическими препаратами (ГИБП) наблюдалось значительное клинико-лабораторное улучшение: снижение активности заболевания (медиана, Ме SLEDAI-2K исходно – 12 [9,5; 17] баллов, на момент визита 4 – 2 [2; 6] балла), Ме концентрации антител к двуспиральной ДНК – АТ к дс-ДНК (101 [39; 250] и 28 [6; 112] Ед/мл соответственно), С3-компонента комплемента (0,44 [0,39; 0,59] и 0,83 [0,81; 0,87] г/л соответственно), С4-компонента комплемента (0,06 [0,031; 0,1] и 0,16 [0,15; 0,18] г/л соответственно). Большинство пациентов получали средние и низкие дозы пероральных ГК в качестве инициирующей терапии. За год доза ГК была уменьшена более чем на четверть, а у части больных удалось полностью их отменить.Заключение. Комбинированная терапия ГИБП с применением РТМ и БЛМ является перспективным методом лечения активной СКВ. Использование такой схемы способствует быстрому и эффективному снижению активности заболевания, нормализации лабораторных маркеров СКВ (уровня АТ к дс-ДНК, С3-, С4-компонентов комплемента), уменьшению дозы пероральных ГК и как следствие – риска развития необратимых органных повреждений